To provide the tread surface of a shoe bottom with friction engendering means in the form of nubs or ribs distributed over the forepart and heel ends of the sole is, of course, not new in the art and various patterns of distribution are disclosed in the following U.S. Pat. Nos.:
2,557,946 PA1 3,444,632 PA1 3,808,713 PA1 3,824,716 PA1 4,044,479 PA1 4,141,158 PA1 1,607,375 PA1 1,979,391 PA1 2,155,166
Conventionally, the nubs or ribs as shown in the aforesaid patents are designed for improving traction and, for the most part, are designed for road work as distinguished from boating and the structures shown in these patents fail to meet the requirements for boat use wherein the presence of a film of water so reduces the frictional resistance to sliding that the conventional protrusions, ribs and the like afford very little resistance to slip. A purpose of this invention is to provide a bottom so structured that movement of the bottom parallel to the surface on which it rests will wipe it dry to thus allow a novel friction engendering surface inwardly thereof to become efficiently resistant to slip.
Another purpose is to provide a unique surface structure at the bottom which is self-cleaning in that it will, when flexed, eject grit and small pebbles and thus minimize damage to smooth, fiberglass, gel-coated and painted surfaces.